1. Field of the Invention
The present invention relates to a multicolor electroluminescent device of a flat-panel display type, and to a process for fabricating the same.
2. Related Arts
Multicolor light-emitting device structures using electroluminescent devices known heretofore include those comprising a plurality of luminescent regions differing from each other in luminescent color, the luminescent regions being arranged in a same plane and interposed between insulating layers.
In the electroluminescent devices of this type, the luminescent regions differing in color also differ from each other in luminescence threshold voltage (a voltage for triggering light emission). Accordingly, means for realizing a uniform luminescence threshold voltage for the luminescent regions have been heretofore proposed in, for instance, unexamined Japanese Utility Model publication Hei-5-11392. The structure disclosed therein comprises a first luminescent portion containing a manganese-doped zinc sulfide (ZnS:Mn) and a second luminescent portion containing zinc sulfide doped with a rare earth element (ZnS:RE, where RE represents a rare earth element) arranged in a same plane in such a manner that the first and the second luminescent portions are in contact with each other to form a dichromatic luminescent layer. The publication further discloses that the structure constructed as above should include a dielectric layer interposed between the first luminescent portion and an insulating layer which envelops the luminescent layer. Though the luminescence threshold voltage of the first luminescent portion is lower than that of the second luminescent portion, the interposed dielectric layer lowers the voltage applied to the first luminescent portion for a voltage corresponding to that applied to the dielectric layer, and thus, the same drive voltage can be applied to the first and second luminescent portions.
Furthermore, in the electroluminescent devices above, it is necessary to prevent crosstalk of light from occurring between the luminescent regions. For instance, a structure disclosed in unexamined Japanese Patent publication Hei-4-39894 comprises light-absorbing materials interposed between the luminescent regions as light shielding films.
However, no effective means has yet been disclosed for a structure in which the luminescence threshold voltage is adjusted and in which crosstalk of light is circumvented at the same time.